Electrical protective device



B. H. S-MITH.

ELECTRICAL PROTECTIVE DEVICE.

APPLICATION FILED APR. 5. 1916.

WITNESSES INVENTOR Ben amin /7'. J'm/ 1/7.

3 I v ATTORNEY Patented Sept. 28,1920.

UNITED STATES PATENT OFFICE.

HOUSE ELECTRIC AND MAN'UFACTUEING CGMPANY, A CORPORATION OF PENN- SYLVANIA.

ELECTRICAL ERGTEQTIVE DEVICE.

Application filed April 5,

time-limit relays.

The object of my invention is to provide a relay of the above indicated character that shall be cheap to construct and efficient and positive in its operation.

Copending' U. S. application Serial No. 771',S8S,filed June 5, 1918, by Almon W.

Copley and Benjamin H. Smith, and asi si ned to the l Vestinghouse Electric and Manufacturing Company, discloses a relay that is provided with a normally-saturated transformer'for the'pur'pose of'producing a definite time element in the operation of the relay. In my present invention,'T provide a similar relay, but, instead of inductively connecting the two main windings of the relay through s'aturatable transformer, I connect the two fwindings in parallel" relation and cause theinimpedances to be'su'ch that the phase-angular relation between'the currents traversing "the two windings shall vary in accordance with the current traversing the circuit to be protected My inventionis primarily intended as a relay but may be adapted to other applications. "It is to be understood, therefore, that the references to relays in the following description donot' limit the application of the invention or restrict the scopeof the claims. 'Inthe accompanying drawing, Figure 1 is a diagrammatic view ofan electric circuit in which is connected a relay embodying my invention, and Fig. ais'a diagram illustrating'theloadtime curve obtainedwith a 'relay embodying my' invent'ion;

An electrical circuit 1 i's'provided with an interrupter 2, 'atrip coilfB thereforand a time-limit relay i that is supplied with current through a tran's'former'5. The relay 4 is provided for controlling the circuit of the trip coil"3 and operates in a manner hereinafter more fully setforth.

"The relay comprises a magnetizable core Specification of Letters Patent. Patented Sept, 28,1920,

1916. Serial No. 89,068.

member 6 having a main current winding 7 and auxiliary windings 8 thereon. Anarmature 9 is mounted on a shaft 10 and is adapted to turn in the air gap of the magnetizable member 6 and also between the poles of a permanentdamping magnet 11 for the purpose of retarding its motion. A bridging contact member l2is mounted on the armature 9 and is adapted to engage stationary contact members 13 for the purpose of operatively connecting the trip coil" 3 to the secondary winding of the transformer 5. Vhile I have shown the trip coil 3 as adapted to be supplied with energy from the transformer 5, it may, of course, be supplied with energy from any other source of electromotive force,

The winding 7 of the relaye is connected to the secondary winding of the transformer 57 and, consequently, is energized in accordance with the current traversing the circuit 1. The windings 8 are connected in series with a reactor 14, and the circuit,'thus constituted, is connected inparallel relation to the winding 7. Thus, thewindingsS are energized by current that is proportional to the current traversing the circuit 1. Howcore member 6 which will co'riperate to cause the armature9 to turn. The phase-angular relation between the currents in the windings? and 8, at relatively low overloads, is such that the speed of rotation of the armature 9 will vary in accordance with the current traversing the circuit However, when a predetermined load is reached, the

magnetiriable core member 6 becomes saturated and the phase-angular relation between the currents traversing the windings' will so vary that the armature 9 will turn at a predetermined definite speed, irrespective of the load traversing the circuit 1. That is, under normal overloads the impedance of the windings 7 V and 8 is such that an excessive overload traverses the circuit,

the relation between the impedance of the 5 windings 7 and 8, by reason of the saturation of the core member, is such that the phase-angular relation will change. Since the speed of the armature 9 varies in accord :ance withthe flux induced in the core member 6 and the phase-angular relation between the currents traversing the cooperating windings, if the phase-angular relation is so shifted that the speed is decreased and .the'cfluxrema ins substantially constant by reason of the core member becoming saturated, the speed of the armature may be substantially constant for all values of overload aboveaipredetermined value. This will be Qreadily seenin the diagram shown in Fig. 2 of the drawing, in which instance, when the fcurrenttraversing the circuit l is A 1 amperes, the time required for the contact member 12to bridge the contact members 13 will be a constant value B.

A spring 1511s connected, at its inner end, to the shaftlO and,at its outer end, to a stationary member 16, and is adapted to cooperate with the damping magnet 11 to obtain various time-element characteristics within the limits afforded by the relay.

' I have described the particular operation of myinvention, together with an arrange ment of parts which is now considered preferable,'biit I do not limit my invention exceptas set forth in the appended claims.

I claim' as my invention: v

1 -1.. A relay for an electric circuit com- V prising a magnetizable core member, two cooperating parallel-connected current windingstherefor,'and an armature, portions of the core member being adapted to become magnetically saturated when a predetermined current traverses the circuit whereby .thephaserelation of the currents traversing 4:5

the. two windings so shifts that the armature develops substantially constant torque for all values of current above the; predetermined value. r V 7 2. A relay; for an electric circuit comprising a magnetizable core member, two cooperating parallel-connected current windings therefor, and an armature, portions of the core'member that are surrounded by one of the windings beingadapted to become magnetically saturated under predetermined con'ditions whereby the phase relation of the currentsgtraversing the two windings so shifts that the armature develops a substantially constant torque. 60 3.

A relay'for an electric circuit comprising a'magnetizable core member, a current winding disposed thereon, an armature, and. an auxiliary winding "connected "in parallel relationto the current winding, said core member being of such cross-sec- ;operates at a constant {speed for all said" windings being adapted to actuate the armature 1n 1 accordance tional areathat the impedance of one of the windings so changes under predetermined overload conditions that. the rate of speed of the armature is substantially con stant' for all values of,load above the-predetermined overload. 7 i I 4. A relay comprising w a magnetizable core member, a current winding, an armature and an auxiliary winding connected tions of the currents traversing the windings to be shifted with respect to each other.

5. A relay comprising a magnetizable core member, a current WlIl Cl1I1g, 2L I1 armature and an'aumliary winding connected in parallel-relation to the current-winding,

the portion of the core member upon which the auxiliary" winding is disposed .being' adapted tobecome magnetically'saturated under predetermined load conditions in the relay to cause the phase-angular relations between the currents in the'windings to be so shifted that the armature will develop a constant torque above that predetermined load. a V

q '6, A relay comprising a} magnetizable core member, a current winding, an armature and an auxiliar windin connected in I V 7 a V b V I I I parallel-relation to the ,current wind ng. the

portion of the core 'member upon which one of the windings is disposed being'adapt- I ed to becomejmagnetically saturated under predetermined load conditions to so shift the phase-angular relation of the currents traversing the windings thatthe armature above the predetermined load. I

7. relay for an1 ,electr1c-. circuit comprising a magnetizable core memberand two parallel-connected windings-supplied with currents proportional to the current traversing' the circuit, portions of'thev core member being adaptedfto become magnetically saturated to cause thephase-angular relation ofthe currentsin the two windings to vary in accordance with thecurrent t'r'av- .ersing the -circuit.- V V I 8, A relay comprising a magnetizable core member, a 'currentwinding, an armature, and an auxiliarywinding connected in loads 1 parallel relation to ;the current winding,

traversing the windings up -to.;a predete'n.

mined value ofcurrent; and the magnetizable core mature is actuated at a substantially conwith the current stant speed for all values of current above the predetermined value.

9. A relay comprising a magnetizable core member, a current winding, an armature, and an auxiliary winding connected in parallel relation to the current winding, said windings being adapted to actuate the armature in accordance with the current traversing the windings up to a predetermined value of current and the portion of the core member that is surrounded by the auxiliarly winding being adapted to become magnetically saturated at that value of current to so shift the phase relation of the currents traversing the windings that the armature is actuated at a substantially constant speed for all values of current above the predetermined value.

10. A relay for an electric circuit comprising a magnetizable core member, two cooperating parallelconnected current windings therefor, and an armature, portions or the core member being adapted to become magnetically saturated to cause the armature to develop a substantially constant torque for all values of current traversing the circuit above a predetermined value.

In testimony whereof, I have hereunto subscribed my name this 31st day of March,

BENJAMIN H. SMITH. 

